


opening the floodgates

by extra kanin (gracon_bacon)



Series: Requested Works [21]
Category: Haikyuu!!
Genre: Alternate Universe: Alpha/Beta/Omega Dynamics, Anal Fingering, Car Sex, Discussions of mpreg, Established Relationship, Hand Jobs, Knotting in Hand, Lactation Kink, M/M, Male Lactation, MiyaMIya2020, Sibling Incest, Size Kink, Twincest
Language: English
Status: Completed
Published: 2020-07-13
Updated: 2020-07-13
Packaged: 2021-03-04 22:48:56
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,515
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25244164
Author URL: https://archiveofourown.org/users/gracon_bacon/pseuds/extra%20kanin
Summary: “The faster you finish here, the sooner you can suck on my tits.”
Relationships: Miya Atsumu/Miya Osamu
Series: Requested Works [21]
Series URL: https://archiveofourown.org/series/1462471
Comments: 13
Kudos: 404





	opening the floodgates

**Author's Note:**

  * For [DalHnrz](https://archiveofourown.org/users/DalHnrz/gifts).



> This fic was requested by the AWESOOOME DalHnrz, who gave me a chance to play around with the twins 🤤 Thank you so much! This hit pretty much every guilty pleasure of mine and it still amuses me that this is officially my first Haikyuu fic 🤣 
> 
> Just in time for Miyacest Week 2020 - Day 4: Alternate Universe too!
> 
> Please read the tags before continuing with the fic! If the tags squick you out, please turn back now 😊 Don't like, don't read!
> 
> Otherwise, I hope you'll enjoy this humble meal (´▽`ʃ♡ƪ)
> 
> If you'd like to request a fic, you may check my [twitter](https://twitter.com/galayugmagay/status/1282719633393549314?s=20) for request info (✿◡‿◡).

“One curry tuna please!”

“Me too!”

“Make that three, please!”

“Comin’ right up!” Osamu answers the throng of students lining up in front of him as he gets started on their orders. Three curry tuna, two umeboshi, and four Miya Surprise…

This wouldn’t be as difficult if Atsumu wasn’t sitting beside the booth, gleefully signing autographs while munching on his third plate of curry tuna onigiri. If Atsumu wasn’t stuffing his face with food then he would be complaining about wanting to go home already, so Osamu just keeps the omega fed and watered. He doesn’t mind his brother’s whining — after all, it’s good for business to have a star athlete attracting customers like flies to honey — but it does grate on his nerves a little to see all the starstruck kids flocking around his mate. 

He wouldn’t trade it for anything though; it’s sweet for Atsumu to keep coming here even after off-season practice, and if that means having to develop nerves of steel and an extraordinary focus on his craft, Osamu would gladly keep suffering like this.

So when Atsumu sidles up to him while he’s forming a rice ball in his hands, he doesn’t really think much of it. Then the omega presses up against his back, deliberately nosing the long hairs behind his ear, and whispers:

“The faster you finish here, the sooner you can suck on my tits.”

Osamu clenches so hard he breaks the onigiri in his hand, spilling rice and curry tuna onto the chopping board. The omega behind him only chuckles and moves away, leaving Osamu with a mess of rice and fillings in his hands, and a giant boner tenting his work apron.

He’d never closed shop earlier than now.

His mate is nowhere to be found as he finishes up. Arousal still buzzing under his skin, Osamu gets to the empty parking lot and loads his tools into the old SUV their mom loaned him for his business. When he gets into the car though, the cheeky little shit is there, lying on the reclined passenger seat with a knowing smirk. “What took ya so long?”

“Ya fuckin’—” Osamu growls and pounces on his brother, crawling over the driver’s seat and straddling the omega’s thighs before going straight for Atsumu’s neck. The alpha digs his teeth into their mating bond mark, pulling a pleased hum from his mate. There’s a faint whiff of the omega’s scent even under all the blockers — a sure sign that Atsumu’s just a few days from heat. _Of course_. Atsumu planned this. He always does when he’s playing Osamu like this. 

As he nibbles on his brother’s neck, the alpha slides a finger under the hem of Atsumu’s spandex top, pushing it up in one swift stroke. The omega’s swollen tits bounce luridly, looking even plumper than usual with how they’re pushed down by the bunched-up fabric of his top. They’d grown bigger over the off-season with Osamu’s constant nursing, and if he didn’t know any better, he would think Atsumu was pregnant. With both of them on the pill, there’s virtually no chance of them getting pregnant, but even then...

The thought of his brother ripe and leaking makes his mouth water. He doesn’t hesitate; he attacks his brother’s breast, gnawing on the soft flesh as he sucks hard on the dusky nipple between his lips. Atsumu tastes like salt and sweat, yet there’s an undercurrent of cinnamon underneath that Osamu can never get enough of. The pleased rumbling from Atsumu only urges him on too as he cups the other breast in his hand, squeezing it as he lavishes his attention on its twin.

“Fuck, Samu… Ya like it that much, huh?” Atsumu sighs out, digging his hands into the alpha’s hair and pushing it back. But when Osamu looks up, his brother’s flushed face betrays just how much the kinky fucker likes it too. 

So he gives the man a show, pursing his lips first before gently dragging his teeth on Atsumu’s flesh, pulling back until only the bud is in his teeth’s grip. Then he pulls hard on it, earning a harsh breath from the omega, before letting it go, giving Atsumu no time to recover as he laps at the stiffened bud and does it again.

In no time, the omega’s started squirming under him, lewdly pressing that breast harder onto his mouth. Osamu doesn’t stay with it though; he switches to the other breast, suckling on it vigorously as he drags his hand down to slip under the waistband of Atsumu’s shorts. 

Atsumu’s so hard it’s a surprise he wasn’t whining more. He only squeezes the omega’s clothed hardness once before dipping his hand even lower. Much to Osamu’s surprise, Atsumu’s slick has gathered into a pool inside his briefs, bulging out from the sheer volume of it. “Damn. Speak for yerself, Tsumu.”

The omega’s laughter breaks into a moan as Osamu presses two fingers down on the source of the wetness. He can feel the furls of Atsumu’s hole against his fingers, and it’s so wet he can even dip a fingertip through the cloth and into the omega. The rough feeling makes Atsumu whine in discomfort, hissing out his name. “Samu—”

Taking pity on his brother, Osamu shoves the cloth aside, biting hard on Atsumu’s tit as the pooled slick gushes out, making a mess of Atsumu’s shorts. The slide of fingers on sensitive flesh makes Atsumu gasp and spreads his legs wider, moaning as Osamu’s hand makes a beeline to his sopping hole. 

It’s so wet and relaxed he easily wedges two fingers inside. He pushes them into Atsumu as far as they can go, grinning on the flesh in his mouth as the omega bucks under him. He can’t reach Atsumu’s prostate in this position, but he doesn’t need to. The omega’s never needed that to come anyway. No, Atsumu’s never cared about depth. But girth…

No one — not that Osamu would know — is a greater size queen as Miya Atsumu.

In this position, it’s more difficult to slip a third finger in, but Osamu perseveres anyway, stretching and massaging the rim until he finally gets it inside. Atsumu’s panting hard above the alpha, tilting his hips up and begging, “Give me more, Samu—Ah!”

The omega cries out as Osamu spreads his fingers, stretching the hole as he pumps in and out of it, gentle at first but growing more forceful at every thrust. As more of Atsumu’s scent comes out, filling the car with its sweet, heady aroma, Osamu nurses even harder on his mate’s breast. He can’t take it anymore; he uses his free hand to unzip his pants, pulling out and pumping his own engorged cock as Atsumu strains under his weight.

Then, when he’s sure the omega’s loose enough, he slips his pinky finger in at the next stroke, and Atsumu screams. “SAMU!”

That’s all it takes for Atsumu to come in his briefs, cock twitching against the alpha’s forearm a few times before finally stilling. Osamu moans around his mouthful as Atsumu tightens, taking harsh, stuttering breaths before letting out a weak whimper. 

When a warm, strangely sweet taste floods Osamu’s tongue, their eyes both widen as they realize…

Atsumu’s leaking. Warm, sweet milk. Actual breastmilk.

Osamu doesn’t waste any of it. He drinks in every last drop, eyes fluttering at both the taste and the quivering of Atsumu’s muscles around his fingers. When he’s sucked his mate dry, he pulls his sodden fingers out of Atsumu, bringing his slick hand to his aching cock and pumping himself in harsh, hard strokes.

He whines as Atsumu’s hand clamps down on his growing knot, his mate dragging him into a bruising kiss as his knot is enclosed in a tight vice grip. It’s all he can do to break the kiss, gasping out, “Tsumu, I’m gonna—,” before he comes, painting the omega’s abs with thick, white ropes of alpha seed.

Still panting from his high, Osamu rests his head on Atsumu’s neck, licking lazily at their mating bond mark as teeth nip on his own mark too. Breathing in each other’s scents, Atsumu chuckles underneath him. “I can’t believe ya managed to _milk_ me, alpha.”

Osamu scoffs. “All the sucking in the world wouldn’t make ya lactate if ya weren’t ripe already.”

A short snicker, and in a light tone, “What if I’m pregnant?”

“Then we’ll be parents,” Osamu says without hesitation. “If the kid manages to get through all of our birth control, then they deserve to be born, don’t they?”

Atsumu chuckles under him, opening his mouth to say something, only for the seat to creak ominously under them. Osamu quickly sits up and pulls Atsumu with him just as the seat’s back breaks, snapping and detaching from its hinges and dropping down to the backseats behind them.

Looking down at the broken seat, they just stare at it for a few seconds before Atsumu shakes his head. “Ahh, Samu, ya better have a good excuse for this. Mom’s gonna to _kill_ us.”


End file.
